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I ' monitorrrr1 e�erit %I 113L %%as detr.cted in samples DDN and DDS (980 and 3 500 pg1l Ic.specttvLly) at • srgnrflcantly I11glter �.onLLrttrations than in preNious and subsequent monitoring events additionally, the only sulfaee ktiatcr sample dLtLLtlons of I AME- wcic, reported in samples DUN and DDS durmi~ the lust quarter, 1999 Itlnnit0iIII! eVLlit Dining thy, third quarter monitoring e%ent however MIBI was dct"tLd in ,arnple DDN at ,i HILIL11 lo,.rer LOIILLntration ( 1 7 tigll} acid %ras not detected in sample DDS M 113F was dLtCLted for the third time in the ,ample collected troll) IDC W (1 6 4g1) ' On lkceiribLi 22 1999 ( ondor conducted fourth quarter 1999 groundwater and surface water monitoring at the site I aborator. analytical results of the groundwater samples collected during tine fourth quarter 1999, ' monitoring Lvint were generally c.oiisistent with historical quarterly Groundwater analytical data Ben/enc and total xylLries were. detected for the second trine in the groundwater Sample collected from MW-3 ' Groundwater LJCN atron measurements collected at the site on Dce.ember 22 1999 indicated that the average, depth to -groundwater was approximately 6 6 feet below the monitor well and surface, water station measuring points 1 his average depth to water was 0 1 feet greater than measured on September 23, 1999 (rroundwater elevation contours for December 22 1999 Indicated that the groundwater gradient at the site was generally ' consistent with the. historical groundwater gradient The laboratory analytical surface water sample data for the fourth quarter, 1999, monitoring event were generally representative of historical data, with the exception of the first quarter 1999, data During the first quarter, 1999, monitoring event, MTBE was detected in samples DDN and DDS (980 and 3,500 µg/l, respectively) at ' significantly higher concentrations than in previous and subsequent monitoring events Additionally, the only surface water sample detections of I AME were reported In samples DDN and DDS during the first quarter, 1999 monitoring event Dining the fourth quarter, 1999 monitoring event, however, M781 was detected in samples DD'V and DDS at much lower coneentratcons (2 7 and 1 5 4g/l rf-%p(ctrvcly) On March 17 2000, C ondor conducted quarter ly groundwatLr and surface water monitoring at llcrman & Helen's Marina located at Venice Island I•crry in Stockton, California Laboratory analytical results of the: groundwater samples collected during the first quarter, 2000, monitoring event are generally consistent with historical quarterly groundwater analytical data ' Groundwater elevation measurements collected at the site on March 17, 2000, indicated that the average depth to groundwater was approximately six feet below the monitor well and island drainage channel water surface measuring points Groundwater clevatron contours for March 17 2000 indicated that the groundwater gradient at the site is generally consistent with the histol ical groundwater gradient Historical Iaboratoiv analytical results indicated that generally low concentrations of MTBE have been present rn at least one of the sui face water samples collected during the surface water sampling events Dur Ing the first quarter, 1999 monitoring event, however, MTBE was detected In samples DUN and DDS (980 and 3 500 fig/l, Iespectively) at significantly higher concentrations than In previous and subsequent momtoiing events I Additionally the only surface water sample detections of TAME; were reported in samples DDN and DDS during the first quarter 1999 monitoring event During the first quarter, 2000, monitoring event, MTBE was again detected at an elevated concentration in surface water sample DDS (4,700 µg/l) (err Iunc 21 2000 ( ondol conducted quartc.iby y1roundv atei and suifau y�atei monitoring at I leiman & Helen's Marina located at Venice Island Ferry in Stockton, California Laboratory analytical results of the groundwater samples collected during the second quarter, 2000, monitoring event are generally consistent with historical quarterly groundwater analytical data MTBE: was detected at low concentrations to surface water samples DDS • (5 0 ugd) and 1D( W (3 2 µg/1)